Yes, follow these steps:
- While you are connected, download the games you want to be able to play.
- Click on SETTINGS.
- You will see your WiFi settings.
- Click on the FORGET button to the right of your current connection.
- You are now offline and can play anything you have installed.
NOTE: Selecting any functions that require online features will result in messages or spinning icons. Unplugging and plugging back in does not change it as long as you do those steps.